(1) Field of the Invention
The present invention relates to a method of producing a plasma display panel used as a display of a color television receiver or the like.
(2) Description of Related Art
Plasma display panels (hereinafter referred to as PDPs) have recently received attention as display apparatuses suitable for computers and televisions, being thin and light with large screens. The demand for high-definition PDPs are also increasing.
FIG. 20 is a schematic sectional view of a typical AC type PDP.
As shown in FIG. 20, a display electrode 102 is formed on a front glass substrate 101, and the display electrode 102 is covered with a dielectric glass layer 103 and a protection layer 104 that is made of magnesium oxide (MgO).
Address electrodes 106 and barrier ribs 107 are formed on a back glass substrate 105. Phosphor layers 110-112 of colors red, green, and blue are formed in spaces between barrier ribs 107.
The front glass substrate 101 and the back glass substrate 105 are formed to face each other with the barrier ribs 107 in between. Discharge spaces 109 are formed by enclosing a discharge gas into each space surrounded by the front glass substrate 101, back glass substrate 105, and barrier ribs 107.
As discharges are caused in the discharge spaces 109, vacuum ultraviolet rays (their main wavelength is 147 nm) are generated. The generated vacuum ultraviolet rays excite the phosphor layers 110-112 to emit light. This allows the PDP to display color images.
Typically, the above PDP is produced as follows.
The display electrodes 102 are formed by applying silver paste to the surface of the front glass substrate 101, and baking the applied silver paste. The dielectric glass layer 103 is formed by applying a dielectric glass paste to the surfaces of the front glass substrate 101 and display electrodes 102, and baking the applied dielectric glass paste. The protecting layer 104 is then formed on the dielectric glass layer 103.
The address electrodes 106 are formed by applying silver paste to the surface of the back glass substrate 105, and baking the applied silver paste. The partition walls 107 are formed by applying the glass paste to the surface of the layers in stripes with a certain pitch, and baking the applied glass paste.
Phosphor pastes of each color are applied to the space between the barrier ribs 107. The applied phosphor pastes are baked at approximately 500° C. to burn out organic binders (resin or the like) contained in the pastes. This completes the phosphor layers 110-112. (phosphor layer baking process)
After the phosphors are baked, a sealing material (glass frit) is applied to the outer region of the back glass substrate 105, then the applied sealing glass frit is baked at approximately 350° C. to remove resin and other elements from the applied sealing glass frit. (sealing material temporary baking process)
The front glass substrate 101 and the back glass substrate 105 are then stacked so that the display electrodes 102 are perpendicular to the address electrodes 106, the electrodes 102 facing the electrodes 106. The substrates are then bonded together by heating them to a temperature (approximately 450° C.) higher than the softening point of the sealing glass. (bonding process)
The bonded panel is heated to approximately 350° C. while gases are exhausted from inner space between the substrates (space formed between the front and back substrates, where the phosphors are exposed to the space). (exhausting process) After the exhausting process is completed, the discharge gas is supplied to the internal space to a certain pressure (typically, in a range of 300 Torr to 500 Torr).
A problem of the PDP manufactured as above is how to improve the light-emitting efficiency and the color purity.
A number of PDPs are increasingly manufactured using the above-described manufacturing method. However, the production cost of PDPs is considerably higher than that of CRTs. As a result, another problem of the PDP is how to reduce the production cost. One of many possible solutions for the cost reduction is to reduce the work (working time) and the energy consumed in several processes that require heating processes.